EP0120549A1 - Lamp unit - Google Patents

Abstract

The lamp unit 100 comprises a mounting 2, 3, 4, 5 for a bulb 1, and an aperture ring 19, defining an exit aperture. A reflector 10 is positioned to reflect light from the bulb 1 to generate a light beam which is directed towards the exit aperture. The light beam converges at a point between the reflector 10 and the aperture ring 19 so that a divergent beam leaves the unit 100. The reflector 10 is supported by a ring 12 integral with a slider 13 which is slidable on the frame 3. Movement of the slider 13 moves the reflector 10 with respect to the bulb 1, and moves the point of convergence towards or away from the aperture ring 19. The divergence of the resultant beam is thereby changed.

Description

• The present invention relates to lamp units. A lamp unit according to the invention may be used, for instance, as one of a cluster of identical units, in an operating theatre table light of the type described in European Patent Application No 83302379.9 of which this case is a divisional.
• A lamp unit according to the present invention is characterised in that it comprises a mounting for a light source, a member defining an aperture, and a reflector positioned to reflect light from a light source mounted in the mounting, to generate a beam which is directed towards the aperture and converges at a point between the reflector and the aperture, the mounting and the reflector being movable one with respect to the other to move the point of convergence towards and away from the aperture.
• One exemplary embodiment of the invention will now be described with reference to the accompanying drawings in which:
• Fig 1 is a perspective view, partially cut away, of a lamp unit according to the invention.
• Fig 2 is a perspective view of part of the structure for supporting the lamp units, to form an operating theatre table light,
• Fig. 3 shows a detail of the apparatus of Fig. 2,
• Fig. 4 is a partly schematic sectional view of the complete light, looking along the axis of the gymbal mounting,
• -Fig. 5 is a schematic perspective view of the complete light, and
• Fig. 6 is a schematic diagram of apparatus facilitating positioning of the light.
• Thelamp unit 100 of Fig. 1 comprises aframe 3 pivotally mounted at 6 and 7 on achassis 8. A bulb 1, preferably a quartz halogen bulb, is located in a hole 2 in theframe 3. The hole 2 is notched to ensure correct alignment of the bulb 1. Alatch 4 retains the bulb 1 in position and can swing away on its mounting 5 to permit bulb replacement.
• The bulb 1 projects through a hole 9 in areflector 10 so that its filament 11 lies on the axis of thereflector 10. Thereflector 10 is supported by aring 12 which is integral with aslider 13 slidably mounted on one limb of theframe 3 to permit the relative position of the filament 11 along the axis of the reflector to be varied. The position of theslider 13 is changed by alever 14 pivoted at 15, and coupled to theslider 13 by alink 16. A spring 17 acts between theframe 3 and theslider 13 to urge the slider in a downward direction. At its second end, thelever 14 is cranked and carries aroller 18 with a V section circumferential groove.
• Thereflector 10 is approximately elliptical when sectioned through its axis, and is preferably dichroic coated to reduce the heat reflected and to control the colour temperature of the light output of the unit. Ellipsoidal reflectors are known as a means of obtaining a converging beam of light. The convergence point and the convergence angle of the rays depend on the relative positions of the reflector and the filament. The apparatus is arranged so that the convergence point always lies between thereflector 10 and anaperture ring 19 mounted on the bottom of theframe 3. To the underside of theaperture ring 19 is clipped a dichroic coatedheat filter glass 20 which has a slightly diffusive surface and below this, a converginglens 21, preferably a fresnel lens. Because the convergence point of the beam is between thereflector 10 and theaperture ring 19, the emergent beam is divergent. The divergence and thus the size of the light patch at a given range is varied by movement of thelever 14.
• Thechassis 8 carries tworollers 22 and 23 set as widely apart as possible and forming with athird roller 24 the corners of an equilateral triangle. Therollers 22, 23, 24 all have V section circumferential grooves. Theroller 24 rotates on apivot 25 which has an adjustable pivot axis. Arigid link 26 is pivotally attached at 27 to theaperture ring 19 so as to be parallel with the axis of the pivots 6 and 7. Above the level of therollers 22, 23, thelink 26 turns through a right angle and has an upper horizontal section which carries twocollars 28 and 29, allowing thelink 26 to slide vertically, but without shake in aslot 30 in thechassis 8. At its upper extremity thelink 26 carries a roller 31 having a V section circumferential groove. Aspring 32 urges the tiltingframe 3 towards thechassis 8 and thus the V roller 31 is urged downwards.
• Ahook 33 is spring mounted on thechassis 8 to project through arectangular aperture 34 in thechassis 8 and to engage the terminal link of aroller chain 35, whose function will be described below. The other end of the chain 35 (not shown in Fig. 1) is bolted to thechassis 8 through ahole 36. Thechassis 8 has sixrectangular apertures 34 andcorresponding holes 36, so that sixidentical lamp units 100 can be connected to respective roller chain bands. The bands are used to change the configuration of the cluster of lamp units.
• Electrical connection to the lamp units is provided through two double endedspring brushes 39 and 40, mounted on thechassis 8 by means of aninsulating mount 38. Eachbrush 39, 40 has a silver contact at each extremity. A conductingwire 41, only partially shown, connects the brush 39 to aconnector 42 which may be pushed onto aspade terminal 43 on the bulb 1. The second terminal of the bulb filament is connected to theframe 3 through the bulb mounting. Aspade terminal 45 is connected to thebrush 40 by a second connector and a second conductingwire 44.
• Referring now to Fig. 2, arigid metal hoop 46 has V section ridges on its edges and its width is such that the tworollers 22 and 23 on each of six chassis can locate on the upper edge, while thelower rollers 24 can locate on the lower edge. The chassis thus mounted externally can move around theaxis 47 of thehoop 46. The lower rollers can be adjusted to eliminate shake when the chassis move on their rollers around the hoops.
• The hoop has stretched around its external face two groups 48 and 49 of three equispaced, square section wires. These wires are small enough to fit between the side links of the roller chains 50 (of which only one is shown in Fig. 2) to form "races" around which the chains can move. The wires 48, 49 are terminated by having their ends bent and passed through the two groups ofholes 51 and 52, and are tied off on the inside of thehoop 46. Equality of lateral spacing of the wires is ensured by short dowels 53, spaced at intervals around thehoop 46.Holes 54 in thehoop 46 allow it to be fixed in the light housing 37 (see Fig. 4).
• Twofurther hoops 55 and 56 are mounted inside thehoop 46 so that thehoop 55 protrudes above the upper edge of thehoop 46, and the hoop. 56 protrudes below the lower edge of thehoop 46. Thehoops 55 and 56 each have threeinclined slots 57 pierced in them approximately equally spaced around the hoops. Twoplain pins 58 in each hoop and one rotatingspindle 59, 60 in respective slots of each hoop mount thehoops 55, 56 on the -hoop 46. Fig. 3 shows in more detail the inside of thehoop 55, and the end of the spindle 59 which is toothed and engages an inclined rack 61 attached to thehoop 55.
• Thetoothed spindles 59,60 are mounted on a pair ofsimilar brackets 63,64. A second pair of brackets is attached to thehoop 46 diametrically opposite those shown in Fig. 2. Each pair meets (at 65 in Fig. 2) to form a bridge over the two groups of wires 48, 49 and provides arobust bearing hole 66 for mounting the light. The spindle 59 carries a toothed pulley wheel 67.which is connected by a toothed drive belt 68 to atoothed wheel 69. The wheel, 69 is carried by a tubular spindle journalled on thespindle 60. Thespindles 60 and 70 both protrude from thebracket 64, and are fitted, outside the housing, withknobs 71, 72 respectively. Rotation of theknobs 71,72 rotates thespindles 60,61 and, through thetoothed ends 62 moves the hoops , 56, 57 around theaxis 47 of thehoop 46. During sucn movement, thehoops 56, 57 are maintained concentric with the main hoop 4t by a multiplicity ofrollers 73 each set in slots cut at the same incline as theslots 57. Therollers 73 run onpin axles 74 so as to roll on the inside surface of thehoop 46. As theknob 71 or 72 is rotated thecorresponding hoop 55, 56 revolves about theaxis 47, and, because theslots 57 are inclined, also moves axially. When a number oflamp units 100 are mounted by theirrollers 22, 23 and 24 on thehoop 46, each has a roller 31 engaging the upper edge of thehoop 55, and aroller 18 engaging the lower edge of thehoop 56. Thus, movement of theknob 72 varies the convergence angles of all the units in unison, through axial movement of thetop hoop 55, thereby changing the patch range. Movement of theknob 71 varies the beam widths of all the units in unison, through axial movement of thebottom hoop 56, thereby changing the patch size. Variations to the patch range and patch size can be made regardless of the positions of thelamp units 100 around thehoop 46.
• Preferably, sixlamp units 100 are used, three being mounted on each semicircular arc of thehoop 46. Thelamp units 100 are moved around thehoop 46 by means of six separate knobs, three being shown in Fig. 2 and three being similarly arranged on .the brackets diametrically opposite those shown in Fig. 2. - Threeknobs 75 are fitted to the lower extremities of respective,vertical shafts 76, 77, 78 which are mounted in bearings in thebrackets 63, 64 so as to be parallel to and equidistant from theaxis 47. Eachshaft 76, 77, 78 carries asprocket 79 which engages arespective roller chain 35; (five chains and the mating sprockets have been omitted from Fig. 2 for clarity). Rotation of any of the sixknobs 75, which are located outside the light housing, moves the respective roller chain along its race and adjusts the position of its associatedlamp unit 100, thereby changing the configuration of the cluster.
• Figs. 4 and 5 are simplified views of the complete light. Fig. 4 shows schematically two of the sixlamp units 100, the beards. of which shine through clear,curved windows 80 in the underside of thetoroidal housing 37. Thetoroidal housing 37 is made of a lightweight material and has a cross section which provides a streamlined-flow of sterile air passed the housing, and prevents drips of condensation forming.
• Tne complete light is supported by ahalf gymbal 81 through a pair ofpivots 82 which engage the pivot holes 66. Electrical power is provided to the lamp unit through twowires 83 and 84 in respective limbs of thegymbal 81. Thewires 83, 84 pass through the hollow bearings and are connected to respective conducting tracks 84 on thehoop 46, which is made of an insulating material. The brushes 39,40 (see Fig. 1) on each lamp unit make electrical contact with the silver plated tracks 84.
• In order to aid the correct targeting of a multilamp light such as that described above it is helpful to provide a fine, intense, collimated beam of light along theaxis 47 of thetoroidal housing 37. For this purpose a streamline section tube 85 (Fig. 6) extends across the central hole of the toroidal housing, preferably along the axis of thebearing 82. Thetube 85 has anaperture 86 on the underside, aligned with theaxis 47 of thehousing 37. Amirror 91, preferably dichroic coated, over theaperture 86 is set at 45° to this axis and to that of thetube 85. A bulb 88 preferably a halogen bulb is mounted inside thetube 85 at one end thereof with the axis of the filament coincident with the axis of thetube 85. Alens array 89 focuses the image of the filament into a thin pencil of light 90 which is reflected through theaperture 86 of themirror 91. Aspherical mirror 92 may be placed behind the bulb 88 to increase the beam intensity. Acoloured filter 93 is mounted between thelens array 89 and themirror 91 on thespindle 94 so that it can be moved into or out of the light beam as required, by turning theknob 95.

Claims (10)

1. A lamp unit (100) characterised in that it comprises a mounting (2, 4) for a light source (1), a member (19) defining an aperture, and a reflector (10) positioned to reflect light from a light source (1) mounted in the mounting (2, 4), to generate a beam which is directed towards the aperture and converges at a point between the reflector (10) and the aperture, the mounting (2, 4) and the reflector (10) being movable one with respect to the other to move the point of convergence toward and away from the aperture.

2. A lamp unit according to claim 1, characterised in that the aperture-defining member (19) is a ring defining a circular aperture.

3. A lamp unit according to claim 1 or 2, characterised by a frame (3) supporting the mounting (2, 4), the aperture-defining member (19) and the reflector (10), the reflector (10) being slidably mounted on a portion of the frame (31).

4. A lamp unit according to claim 1, 2 or 3, characterised by a housing (37) around the mounting (2,4), the aperture-defining member (19) and the reflector (10), and means (75) operable from outside the housing for moving the reflector (10) and the mounting (2, 4) one with respect to the other.

5. A lamp unit according to any of claims 1 to 4, further characterised in that the reflector (10) is dichroic coated.

6. A lamp unit according to any of claims 1 to 5, further characterised by a dichroic coated heat filter (20) in the path of the light beam.

₇. A lamp unit according to claim 6, characterised in that the heat filter (20) is downstream of the aperture-defining member (19).

8. A lamp unit according to any of claims 1 to 7, characterised by a converging lens (21) in the path of the light beam downstream of the aperture-defining member (19).

9. A lamp according to claim 8, characterised in that the converging lens (21) is a Fresnel lens.

10. A lamp unit according to any of claims 1 to 9, characterised in that the reflector (10) is a concave ellipsoidal reflector.

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